[tip: sched/core] sched: add READ_ONCE to task_on_rq_queued

[tip-bot2 for Harshit Agarwal]

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     59297e2093ceced86393a059a4bd36802311f7bb
Gitweb:        https://git.kernel.org/tip/59297e2093ceced86393a059a4bd36802311f7bb
Author:        Harshit Agarwal <harshit@xxxxxxxxxxx>
AuthorDate:    Thu, 14 Nov 2024 14:08:11 -07:00
Committer:     Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Mon, 02 Dec 2024 12:01:30 +01:00

sched: add READ_ONCE to task_on_rq_queued

task_on_rq_queued read p->on_rq without READ_ONCE, though p->on_rq is
set with WRITE_ONCE in {activate|deactivate}_task and smp_store_release
in __block_task, and also read with READ_ONCE in task_on_rq_migrating.

Make all of these accesses pair together by adding READ_ONCE in the
task_on_rq_queued.

Signed-off-by: Harshit Agarwal <harshit@xxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Phil Auld <pauld@xxxxxxxxxx>
Link: https://lkml.kernel.org/r/20241114210812.1836587-1-jon@xxxxxxxxxxx
---
 kernel/sched/sched.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 76f5f53..0f6790c 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -2271,7 +2271,7 @@ static inline int task_on_cpu(struct rq *rq, struct task_struct *p)
 
 static inline int task_on_rq_queued(struct task_struct *p)
 {
-	return p->on_rq == TASK_ON_RQ_QUEUED;
+	return READ_ONCE(p->on_rq) == TASK_ON_RQ_QUEUED;
 }
 
 static inline int task_on_rq_migrating(struct task_struct *p)